Application

Modular design and intelligently connected power electronics

If electromobility is to become a success, then electric vehicles will soon need to be charged much faster. Since the connected load required for this purpose is not available everywhere, it often has to be retrofitted, incurring very high costs. An interesting alternative is the use of batteries as an energy store.

The costs associated with providing the requisite connected load must be reduced, such that developing the charging infrastructure becomes affordable.

“To this end, our batteries can be used as energy storage units,” explains Böden. “The battery storage system is primarily designed for the AC power supply, and supplies the charging stations with direct current on the secondary side.” The storage system therefore provides the power required for charging and is recharged up to full capacity with a low primary power.

Solution

EV CC Professional is the core element for charging station communication and control

The advantage of a battery storage unit compared to a switching device lies in the ongoing electricity costs. A higher base price has to be paid for the high connected load of the control gear, while the price per kWh is low. For the lower connected load of the battery storage system, the basic rate is cheaper, but the costs per kWh are high. “Nevertheless, the storage version with the same investment costs proves to be more economical to operate, since higher amounts can be achieved to pay off the financing than from the direct supply via the medium voltage system,” explains Böden.

A charging infrastructure with high outputs can be integrated and managed in various ways. Each charging point can be controlled such that the available energy is distributed according to the connected load. If two charging points are used by CCS2 (combined charging system type 2) electric vehicles, while the other two charging points are used by fast-charging CCS2-HPC (high power charging) electric vehicles, the power will be distributed unevenly.

In this case, scalable power electronics offer a solution consisting of multiple modules. This could, for example, be 15 units each with an output of 75 kW. The two charging points with CCS2 vehicles are then assigned one 75 kW module each, meaning that the remaining 13 modules can used for the fast charging vehicles. An intelligent matrix would then assign six to one charging point and the remaining seven modules to the other charging point.

This type of energy allocation requires intelligent communication elements, such as the DC charging controller EV CC Professional that is developed, produced and marketed by Phoenix Contact E-Mobility GmbH. It is the key element of such a charging infrastructure and communicates with the individual elements such as the battery storage system and power electronics.

Summary

Coupling the battery with an existing solar plant or wind turbine generator has an even greater positive effect on running costs. It is worth noting that high power charging for standard charging stations is no longer a utopian concept. If integrated within a practical charging infrastructure with other components such as the battery storage system, power electronics and control technology and, if possible, combined with regenerative energies, then HPC charging stations or parking spaces are extremely suitable for ensuring that electromobility is practical to use.